RESUMEN
The main bacterium associated with skin infection is Staphylococcus aureus, occurring especially in infections acquired via surgical wounds, commonly leading to lethal hospital-acquired infections, emphasizing the importance of identifying new antimicrobial compounds. Among them, cyclotides have gained interest due to their high stability and multifunctional properties. Here, cycloviolacin 2 (CyO2) and kalata B2 (KB2) were evaluated to determinate their anti-staphylococcal activities using a subcutaneous infection model. Anti-staphylococcal activities of 50mM for KB2 and 25mM for CyO2 were detected with no cytotoxic activities against RAW 264.7 monocytes. In the in vivo assays, both cyclotides reduced bacterial load and CyO2 demonstrated an increase in the phagocytosis index, suggesting that the CyO2 in vivo anti-staphylococcal activity may be associated with phagocytic activity, additionally to direct anti-pathogenic activity.
Asunto(s)
Antibacterianos/farmacología , Péptidos Cíclicos/farmacología , Infecciones Cutáneas Estafilocócicas/tratamiento farmacológico , Staphylococcus aureus/efectos de los fármacos , Infección de la Herida Quirúrgica/tratamiento farmacológico , Animales , Ratones , Ratones Endogámicos C57BL , Pruebas de Sensibilidad Microbiana , Viabilidad Microbiana , Neutrófilos/efectos de los fármacos , Neutrófilos/fisiología , Fagocitosis/efectos de los fármacos , Células RAW 264.7 , Infecciones Cutáneas Estafilocócicas/microbiología , Infección de la Herida Quirúrgica/microbiologíaRESUMEN
Microbial diversity was evaluated in an anoxic zone of Tucuruí Hydroelectric Power Station reservoir in Brazilian Amazonia using a culture-independent approach by amplifying and sequencing fragments of the 16S rRNA gene using metagenomic DNA as a template. Samples obtained from the photic, aphotic (40 m) and sediment (60 m) layers were used to construct six 16S rDNA libraries containing a total of 1,152 clones. The sediment, aphotic and photic layers presented 64, 33 and 35 unique archaeal operational taxonomic units (OTUs). The estimated richness of these layers was evaluated to be 153, 106 and 79 archaeal OTUs, respectively, using the abundance-based coverage estimator (ACE) and 114, 83 and 77 OTUs using the Chao1 estimator. For bacterial sequences, 114, 69 and 57 OTUs were found in the sediment, aphotic and photic layers, which presented estimated richnesses of 1,414, 522 and 197 OTUs (ACE) and 1,059, 1,014 and 148 OTUs (Chao1), respectively. Phylogenetic analyses of the sequences obtained revealed a high richness of microorganisms which participate in the carbon cycle, namely, methanogenic archaea and methanotrophic proteobacteria. Most sequences obtained belong to non-culturable prokaryotes. The present study offers the first glimpse of the huge microbial diversity of an anoxic area of a man-made lacustrine environment in the tropics.
Asunto(s)
Archaea/clasificación , Biodiversidad , Centrales Eléctricas , Proteobacteria/clasificación , Microbiología del Agua , Archaea/genética , Brasil , ADN de Archaea/genética , ADN Bacteriano/genética , Biblioteca de Genes , Sedimentos Geológicos/microbiología , Filogenia , Proteobacteria/genética , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADNRESUMEN
A sensor based on glassy carbon (GC) electrode modified with cobalt tetrasulfonated phthalocyanine (CoTSPc) and a poly-l-lysine (PLL) film is proposed for diospyrin determination in nanomolar concentrations with differential pulse voltammetry (DPV) technique. The modified electrode showed excellent catalytic activity presenting much higher peak currents than those measured on a bare GC electrode. Linear response range, sensitivity and limit of detection (LOD) were of 1-120nmoll(-1), 220.46nAlnmol(-1)cm(-2) and 0.3nmoll(-1), respectively. The repeatability of the proposed sensor, evaluated in term of relative standard deviation (R.S.D.), was measured as 4.4% for 10 experiments in 50mumoll(-1) diospyrin samples. The developed sensor was applied for the determination of diospyrin in the crude extracts of the stem-bark of Diospyros montana Roxb. and the average recovery for these samples was 101.9 (+/-3.1)%.